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ENCE 3610 Soil Mechanics
University of Tennessee at Chattanooga
Spring 2011
Don C. Warrington, P.E., Instructor
http://www.vulcanhammer.net/utc
Catalog Description
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Geologic overview
Soil composition
Soil type and
structure
Index properties
Classification
Site investigation
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Subsurface flow
Flow nets
Drainage
Subsurface stresses
Settlement
Shear strength
Slope stability
Textbooks
Textbooks
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Das, Braja M. Principles of
Geotechnical Engineering. Sixth
Edition. Stamford, CT: Cengage
Learning, 2006
EM 1110-2-1906, Laboratory
Soils Testing. Department of the
Army, U.S. Army Corps of
Engineers, Washington, DC,
1986.
NAVFAC DM 7.01, Soil
Mechanics. Naval Facilities
Engineering Command,
Alexandria, Virginia, 1986.
Samtami, N.C, and Nowatski,
E.A. Soils and Foundations
Reference Manual. Washington,
DC: Federal Highway
Administration, 2006.
Line Drawing Credit
Dr. Bengt Broms
Foundation Design
http://www.geoforum.com/
Evaluation
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Homework: Seven (7) assignments @ 4%
each = 28%
One (1) Mid-Term Examination: 14%
Three (3) unannounced quizzes @ 4% each:
12%
Six (6) Laboratory Reports @ 5% each: 30%
Final Examination: 16%
Class Notebook
You are required to keep and assemble a
three-ring (or other suitable binding) notebook
with the following divisions in it:
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Homework
Quizzes
Tests
Laboratory Experiment Reports
You will turn this notebook in at the final
exam. It will be inspected and returned to
you.
Course Policies
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Due date for homework assignments will be
announced when assignment is given.
Homework turned in after due date will have
20% deducted from grade for each class
period late. Homework turned in after last
class session will be given a grade of zero.
Attendance is required with the exception of
special arrangements made before class as
the only excused absences.
When applicable, all problems must include
a figure. All figures are to be neat and
legible. Also when applicable, all problems
must include a) Given b) Find c) Solution.
On the first page of each problem set or test,
in the upper right hand corner write a) Your
Name, b) Course Number and c) Problem
Set or Test Number. Any problem set or test
that does not follow these rules or is not neat
will receive reduced credit.

Each time you use an equation,
write down what it is: don't just put
a bunch of numbers on the page
and expect anyone to know what
you did. This too will result in
reduced credit.
 You are encouraged to work
homework with someone but your
turned in work must be your own
work.
 All quizzes and exams are open
book(s) and open notes. You
obviously may use a calculator, but
no laptops or any other internetaccessing devices (iPhone, iPad,
iPod Touch, Droid, etc.) can be
used during a quiz or exam (see
following paragraph for penalty.)
Honor System
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You are encouraged to work homework with
someone but your turned in work must be your own
work.
You are studying now so that you may enter and
practice the engineering profession later. The
engineering profession is highly regarded by the
public because those who practice it do so with
ethical and social consciousness. The same is
expected of students in this course. Any direct
copying of homework, tests or exams will be
considered a violation of the honour code and a
course grade of “F” will be given.
Types of Civil Engineering
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Structural Engineering
Engineering Mechanics
Transportation
Engineering
Environmental
Engineering
Coastal Engineering
Geotechnical
Engineering
Definition of Geotechnical Engineering
“The branch of Civil Engineering
that deals with the properties of
soils and rocks and their
capability of supporting structures
placed on or under them.”
Characteristics of Geotechnical
Engineering
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Works in a complex environment
Requires a higher degree of judgement than
other branches of engineering
More than one “acceptable” solution to any
problem
The integrity of the structure above is
dependent upon the quality of the foundation
below
Development of Geotechnical
Engineering
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The slowest branch of civil engineering to
develop a theoretical basis that could be used
in practical design
Design of foundations traditionally was
conservative and the result of trial and error
Larger structures and catastrophic failures led
to the investigation of the causes of failure
and the establishment of theory which in turn
would lead to design methods that resulted in
workable foundations
Gothenburg Harbor Failure
5 March 1916
Gothenburg Harbor Failure
5 March 1916
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Soft clay deposit,
150' deep
50' was dredged out
and replaced by
sand fill; piles were
driven to stabilize
the quay
Several hundred
feet of wall slid
seaward as shown
Appointment of Swedish Commission
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In 1913, the Swedish State Railroad
Administration appointed a special
Geotechnical Commission – the first so titled
– to study these types of failures and to
recommend a solution
Its chairman, Wolmar Fellenius, developed the
basic methods for analysing rotational failures
of slopes which, with improvement, we use
today
Karl Terzaghi
The “father of geotechnical engineering”
Developed both the theory and practice of the
analysis of soils and the design of foundations
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Consolidation theory
Bearing Capacity of Shallow Foundations
Design of retaining walls and cellular
cofferdams
Wrote some of the first textbooks on soil
mechanics and foundations design
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Soil Mechanics in Engineering Practice (1948)
Theoretical Soil Mechanics (1943)
Soils and Rocks
Definition of “Soil” and “Rock”
Soil
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Naturally occurring mineral particles which are
readily separated into relatively small pieces,
and in which the mass may contain air, water,
or organic materials (derived from decay of
vegetation).
Rock
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Naturally occurring material composed of
mineral particles so firmly bonded together that
relatively great effort is required to separate the
particles (i.e., blasting or heavy crushing
forces).
Types of Rocks and The Rock
Cycle
Igneous Rocks
Definition
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Rocks formed by the
solidification of molten
material, either by intrusion at
depth in the earth's crust or by
extrusion at the earth's
surface.
Sedimentary Rocks
Definition
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Types
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Rocks formed by deposition,
usually under water, of
products derived by the
disaggregation of pre-existing
rocks.
Shales
clay and silt
particles
Sandstones
Limestone (Karst topography)
Dolstone (marl, chalk)
Importance of Weathering
Metamorphic Rocks
Definition
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Rocks that may be either igneous or
sedimentary rocks that have been altered
physically and sometimes chemically by the
application of intense heat and pressure at
some time in their geological history
From Rock to Soil
Weathering of Rocks to Soil
 Weathering is the
physical or chemical
breakdown of rock
 Physical Weathering
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Unloading of
overburden
compressive stresses
Frost Action
Organism Growth
Temperature Changes
Crystal Growth
Abrasion
 Chemical Weathering
 Oxidation
 Hydration
 Hydrolysis
 Carbonation
 Solution
 Especially significant
in the erosion of
limestone and the
formation of Karst
Topography and
sinkholes
Basic Soil Types
Sedimentary Soils
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Soils which are
weathered in place
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Residual
Organic
Transported Soils
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Soils which are
transported and
deposited in a new
location
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Alluvial
Aeolian
Glacial
Marine
Colluvial
Pyroclastic
Sedimentary Soils
Residual Soils: Material formed
by disintegration of underlying
parent rock or partially indurated
material.
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Sands
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Residual sands and fragments
of gravel size formed by
solution and leaching of
cementing material, leaving
the more resistant particles;
commonly quartz.
Clays
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Residual clays formed by
decomposition of silicate
rocks, disintegration of shales,
and solution of carbonates in
limestone.
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Organic Soils: Accumulation of
highly organic material formed
in place by the growth and
subsequent decay of plant life
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Peat. A somewhat fibrous
aggregate of decayed and
decaying vegetation matter
having a dark colour and odour
of decay.
Muck. Peat deposits which
have advanced in stage of
decomposition to such extent
that the botanical character is
no longer evident.
Very compressible. Entirely
unsuitable for supporting
building foundations.
Transported Soils:
Alluvial Soils
Transported Soils:
Alluvial Soils
 Other examples
 Alluvial fans:
water
transported
deposits in
relatively dry
places
 Piedmont
deposits
Transported Soils:
Aeolian Soils
Transported Soils:
Glacial Soils
Transported Soils
Marine Soils: Material
transported and deposited by
ocean waves and currents in
shore and offshore areas.
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Colluvial Soils: Material
transported and deposited by
gravity.
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Shore deposits
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Deposits of sands and/or
gravels formed by the
transporting, destructive,
and sorting action of
waves on the shoreline.
Marine clays
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Organic and inorganic
deposits of fine-grained
material.
Deposits created by
gradual accumulation
of unsorted rock
fragments and debris
at base of cliffs.
Hillwash
 Fine colluvium
consisting of clayey
sand, sand silt, or clay.
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Talus
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Particle or Grain Sizes
Soil Cohesion
Cohesionless Soils
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Generally are
granular or coarse
grained
Particles do not
naturally adhere to
each other
Have higher
permeability
Cohesive Soils
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Generally are fine
grained
Particles have
natural adhesion to
each other due to
presence of clay
minerals
Have low
permeability
Structure of Clay Minerals
Atoms of clay minerals
form sheets
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Silica tetrahedral sheets
Alumina octahedral
sheets
Sheets can layer in
different ways, forming
different types of clay
minerals
Clay minerals tend to
form flat, platelike
shapes
Types of Clay Minerals
Kaolinite
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One sheet alumina, one
silica, sheet of water in
between
Properties affected by
presence or removal of
water sheet
Reverts to kaolinite when
water is removed
Illite
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One sheet alumina, one
silica
Most prevalent clay
mineral
Halloysite
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One silica, one alumina,
one silica sheet, bonded
with potassium
More plastic than kaolinite
Most prevalent in marine
deposits
Montmorillonite
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Same as illite except no
potassium; iron or
magnesium replace the
alumina
Very prone to expansion
with changes in water
content due to weak
bonding
Questions?